I plan to make a Fish and live rock only tank, thats what I gothered from reading is good for a begginner. I set it up on Sun, Jul 6 and I put in a Yellow Tail Damsel, so far no problems. I have foam on the top of the tank, is this normal? I opened the protein skimmer valve (thought it might help).

I have some questions, first what is a cycle and how long is it? what is a sump? (read about in lots of posts). Here is what I would like to put in the tank:

Dwarf lion fish
small eel
1 clown fish
1 yellow tang
1 to 2 other fish (not sure yet, is it too much?)
some starfish
some critters for the sand (which should i get?)

Sorry for all the questions, but this is my first time with sw had fw all my life and never had any major problems.

20 Galon is too small for a yellow tang. they need lost of swiming room. 80 gallon and above. some eel's are escape artists, youll need a tight fitting lid. as for the one to two others maybe a chromis, or flame angle. reserch your stars some will eat corals while others eat fish. brittle (not green) red serpant , and lynkas are good stars.

$$$ permitting I would go 50+ galons for your saltwater. if not, you won't be able to slouch on your maintinence schedual.

finding donations of Live sand is the best way to get critters for your sand, if not able buy some bags of Live sand at the LFS.

ask here first before buying anything. the LFS is not always truthfull when it comes to good advice, and truth usualy takes a chunk out of there profit margin. like most businesses, there strugling to beat prior years sales.

First, I agree with what has already been said. To add a few comments:

20lbs of LR is the absolute minimum if you intend to use the LR as a bio filter. 30lbs...or even as much as 40lbs would be more like it.
The dwarf lion and the eel are both predators. They need high protien foods and will be messy. Translated, this means they both will put a strain on the bio filter. A dwarf lion and one of the smaller eels would be about it for a 20 IMO.
The clown (perc or ocellaris are my favorites) would be good. Maybe a couple of blue or green chromis. There are several fish in the blennies and gobies that would be good for a 20.
I think you'll find, although the Skilter will pull some gunk from the water, that you will want to upgrade the skimmer later. Aqua C Remora makes a good skimmer. Be sure to get the MaxiJet pump though...Rios tend to give trouble.
I would suggest the next money you spend be on a copy of "The Concientious Marine Aquarist" by Robert Fenner. This is an excellent book that covers all aspects of SW and is worded so you don't have to have a Phd to understand it. It will pay for itself quickly.
Although we are happy to answer any questions you have, there is a search option on this site. You might read some of the old posts that relate to things you have questions about...there is a lot of info in the archives.
I don't think the 18" 15w bulb is enough. At the least, you need two of them. If you could find a double strip that uses 24" 20w bulbs, that would be much better. If you're going to use one bulb, I'd go with a 50/50. If two bulbs, I'd use one white (6500-10,000k) and one actinic (blue). A better solution, if it's in the budget, would be a 65w PC 50/50. Custom Sealife makes a light called a Smartlite that would do well unless you want to build your own.
Welcome to AA!

__________________
Life is not measured by the number of breaths we take, but by the moments that take our breath away.
Logan J

Thanks for the advice. Today I dropped by a LFS and picked up a coralite 50/50 and 6lbs of fiji live rock. The LFS told me to put fluval media inside my filter behind the cartridge. Is this a good idea she seem trustfull?. They had some rock with dead coral on it, is this better or worse? 8O